The machine tool with which this turret is preferably used may be described as a mill/turn machine tool which is capable of milling, turning, drilling, tapping, etc. with a rotating or non-rotating workpiece spindle and a rotating or non-rotating tool spindle in the turret.
A number of turrets have been proposed for machine tools. U.S. Pat. No. 3,186,085 shows a two-place turret for non-rotating turning tools used with a rotating workpiece. U.S. Pat. No. 3,186,266 shows a one-place turret, also for non-rotating turning tools. U.S. Pat. No. 3,296,903 shows a turret type of tool magazine for supplying any one of a multiplicity of non-rotating turning tools into an operative position. U.S. Pat. No. 3,316,786 shows a turret type of tool magazine for non-rotating turning tools. U.S. Pat. No. 4,051,583 discloses a turret with two spindles, each of which can be oriented into an operative position. U.S. Pat. No. 4,643,623 discloses a claw clutch which is engaged when the tool holder is not in the tool spindle and disengaged when inserted in the spindle so it is free to rotate. In U.S. Pat. No. 4,570,313, when the spindle is clamped against rotation, any vibration of the tool in the tool spindle mount as the tool works on a workpiece will be transmitted to the ball bearings despite the presence of the interlocking gear teeth. This can have a damaging effect on the bearings because there is no rolling contact at that time, and such vibration would tend to Brinell the surface of the bearing races.
The Yamazaki or Mazak mill/turn 40N ATC mill center machine is a machine tool of the mill/turn type with two tool holders, one of which is rotatable, and the other of which is only fixed. The turret axis is in the x-c plane so that the tool holders are operative in only two different positions, either 0.degree. or 90.degree. relative to the spindle axis c, with x being the cross slide path.